Transcription factors are a group of molecules within the cell that function to connect the pathways from extracellular signals to intracellular responses. Immediately after an environmental stimulus, these proteins which reside predominantly in the cytosol are translocated to the nucleus where they bind to specific DNA sequences in the promoter elements of target genes and activate the transcription of these target genes. One family of transcription factors, the ZAS (zinc finger-acidic domain structures) DNA binding protein family is involved in the regulation of gene transcription, DNA recombination, and signal transduction (Mak, C. H., et al. 1998. Immunogenetics 48: 32-39).
Zinc finger proteins are identified by the presence of highly conserved Cys2His2 zinc fingers (Mak, C. H., et al. 1998. Immunogenetics 48: 32-39). The zinc fingers are an integral part of the DNA binding structure called the ZAS domain. The ZAS domain is comprised of a pair of zinc fingers, a glutamic acid/aspartic acid-rich acidic sequence and a serine/threonine rich sequence (Mak, C. H., et al. 1998. Immunogenetics 48: 32-39). The ZAS domains have been shown to interact with the kB like cis-acting regulatory elements found in the promoter or enhancer regions of genes. The ZAS proteins recognize nuclear factor kB binding sites which are present in the enhancer sequences of many genes, especially those involved in immune responses (Bachmeyer, et al. 1999. Nuc. Acid Res. 27, 643-648). The ZAS DNA binding proteins have been shown to be transcription regulators of these target genes (Bachmeyer, et al. 1999. Nuc. Acid Res. 27, 643-648; Wu et al. 1998. Science 281, 998-1001).
The zinc finger transcription factor Kappa Recognition Component (“KRC”) is a member of the ZAS DNA binding family of proteins (Bachmeyer, et al. 1999. Nuc. Acid Res. 27, 643-648; Wu et al. 1998. Science 281, 998-1001). The KRC gene was identified as a DNA binding protein for the heptameric consensus signal sequences involved in somatic V(D)J recombination of the immune receptor genes (Mak, C. H., et al. 1994. Nuc. Acid Res. 22: 383-390). KRC is a substrate for epidermal growth factor receptor kinase and p34cdc2 kinase in vitro (Bachmeyer, et al. 1999. Nuc. Acid Res. 27, 643-648). However, other functions of KRC and the signal transduction pathways that activate KRC in vivo were not known.
Gene-specific transcription factors provide a promising class of targets for novel therapeutics because they provide substantial specificity and are known to be involved in human disease. A number of extremely effective presently marketed drugs act, at least indirectly, by modulating gene transcription. For instance, in many cases of heart disease, the LDL receptor is pathogenically down-regulated at the level of transcription by intracellular sterol levels. The drug compactin, an inhibitor of HMG CoA reductase, functions by up-regulating transcription of the LDL receptor gene which leads to clearance of cholesterol from the blood stream.
In another example, transcription factors can be modulated to regulate an immune response. In autoimmune diseases, self-tolerance is lost and the immune system attacks “self” tissue as if it were a foreign target. Many autoimmune diseases are presently known, such as multiple sclerosis (MS), rheumatoid arthritis, insulin-dependent diabetes mellitus, hemolytic anemias, rheumatic fever, Crohn's disease, Guillain-Barre syndrome, psoriasis, glomerulonephritis, autoimmune hepatitis, multiple sclerosis, etc. In diseases such as these, inhibiting the immune response is desirable. In addition, inhibiting the body's immune response is beneficial in prevention, for example, of organ transplant rejection. Conversely, enhancing the immune response is beneficial in certain circumstances such as the treatment of AIDS, cancer, atherosclerosis and diabetic complications (Sen, P. et al. 1996. FASEB Journal 10:709-720, 1996).
Urgently needed are efficient methods of identifying pharmacological agents or drugs which are active at the level of gene transcription. Specifically, agents for use modulating such cellular processes in T cells are needed to regulate the immune response. Agents and methods of using such agents in modulation of cell survival, proliferation, differentiation and/or motility would be of great benefit.